(a) Field of the Invention
This invention relates to 3-hydrazino-6-PY-pyridazine, useful as cardiotonic agent, and to its preparation.
(b) Description of the Prior Art
Haginiwa et al. [Yakugaku Zasshi 98 (1), 67-71 (1978); Chem. Abstrs. 88, 170,096v (1978)] reacted 3(2H)-pyradazinone with pyridine 1-oxide and platinized Pd-C catalyst to produce 6-(2-pyridinyl)-3(2H)-pyridazinone.
The Yoshitomi Pharmaceutical Ind., Ltd. Japanese Patent Application Disclosure No. 19,987/79, published Feb. 15, 1979 and based on Application Ser. No. 85,192/77, filed July 15, 1977, discloses, inter alia, the preparation of 4,5-dihydro-6-(4-pyridinyl)-3(2H)-pyridazinone by refluxing for two hours an ethanolic solution of 3-(isonicotinoyl)propanoic acid [same as .gamma.-oxo-.gamma.-(4-pyridinyl)butyric acid] and hydrazine hydrate. 4,5-Dihydro-6-(4-pyridinyl)-3(2H)-pyridazinone and closely related 4,5-dihydro-6-(4- or 3- or 2-pyridinyl)-5-R-3(2H)-pyridazinones, where R is H or lower alkyl, are said (page 2 of English translation) to be "useful not only as medicines such as hypotensive and antithrombus agents because they have pharmacological actions such as hypotensive, blood platelet coagulation-inhibitory and membrane-stabilizing actions, but also as intermediates for the synthesis of such medicines".